Traceable Material Properties with VeriPart

Written by Paul Guerrier

Introduction - Why

Metallic aircraft parts in loaded applications are safe by design. But how do engineers achieve this? Over 60 years ago material strength data under various different loading conditions (static, dynamic, shear, tension etc.) was gathered together by government and later by commercial and not-for profit entities. Today this data can be found in trusted sources such as the Metallic Material Properties Development and Standardization (MMPDS) Handbook.  MMPDS serves as the primary source for statistically based metallic material properties used for strength determinations made by regulatory bodies such as FAA and EASA.

Figure 1 Bar stock Used for Machined from Solid Aerospace Parts

Engineers at Moog and other Aerospace OEMs use the data in the handbook to ensure parts have  adequate strength to achieve load carrying requirements. This works just fine for parts manufactured using current manufacturing processes based on subtractively machined from solid (block) and the approach is well proven.

Figure 2 Scanning Electron Microscope Image of Al Alloy F357 Powder

However, additive manufacturing processes such as: laser powder bed fusion, direct energy deposition or binder jetting present new challenges.  These additive processes create both the part geometry and the material properties during the part build process.  The list of challenges includes:

    1.  The current, published material properties do not cover materials produced via additive manufacturing

    2.  The load carrying capacity (strength) of a material is strongly dependent on the process parameters used at the additive manufacturing equipment.

    3.  Raw material form and chemical composition influence mechanical properties and should be controlled to provide consistent parts.

    4.  Process steps after additive manufacturing such as heat treatment and surface finishing both control factors including: material grain structure, surface roughness and residual stress. All of these factors contribute to the finished part mechanical strength.

Figure 3 Additively Manufactured Link Used in a Helicopter Autopilot

Thankfully, solutions exist to the problems of process control and consistent additively manufactured parts with reliable material properties. 

VeriPart - How

If I am holding a finished additively manufactured part which carries a load and I am planning to fly it how do I know it has been correctly produced? In today’s world, a stack of paperwork with required inspection data, stamps from “Operator Fred” and “Inspector Maggie” and all the other operators and inspectors up and down the supply chain act as a record that everything was done as per the released processes. Of course these stacks of paper have been transformed into PDFs and when production volumes are high enough databases but transactions are largely manually recorded. Confirming all of the manufacturing details of a finished part can be tedious.

VeriPart is a blockchain enabled method for securely recording all of the production processes associated with an additively manufactured part or component. Operators and inspectors would digitally confirm manufacturing process steps to provide a record of component operations (aka. a chain of custody). All process parameters would be recorded locally and linked to from VeriPart. All of the substantiating mechanical testing using the same process parameters would also be linked to from VeriPart. This key step confirms that the part is strong enough to carry the flight loads

In the case of needing to know the history of a loaded part before flight “the stack of paperwork” problem no longer exists. Instead the part number and serial number of the part would be queried in VeriPart and then all of the manufacturing and quality data associated would be accessible, likely from a tablet or smartphone.

Conclusion - Next Steps

VeriPart is real, demonstrations have been completed and implementations exist. If you want to know more take a look at Moog’s dedicated website